Building A Rock Garden

The hardest task in gardening is to make the artificial look natural. As the Roman poet once said: ars est celare artem: "True art is to conceal art." Here stone, foliage, and blossom come together in happy combination.

One of the great things about working in design is that you get a chance to experience a wide range of mediums, far greater than you would ever have in even the most ample single garden. Recently I was called out to redesign a pool deck in nearby Sudbury, Massachusetts. The setting was spectacular – a 10′ raised deck overlooking fields and pasture – but the large crescent surrounding the pool had been planted with a boring line of perennials with little seasonal interest other than midsummer. This was the view in May:

Taking my theme from the many Colonial era stone walls on the property, I decided that this would be the ideal setting for a rock garden: the stones would add year round interest and three dimensionality to the flat deck, and combined with plantings, would merge into the perfect foil for the greens and blues of field and sky beyond.

Great idea, but rock gardens are tricky: well designed they look like they have been there forever the second after they’ve been installed. Badly done, they look tacky  think the brown lava rocks, clorinated stream and musak from speakers hidden in ficus, courtesy your average 70s shopping mall. The key to making rock gardens look good is threefold: you need interesting stones; you need stones of varying masses; and you need to use plant material that’s looks natural.

In this case, the first part was well in hand: behind the clients’ barn was a huge pile of stone that once formed a sheep ramp into the structure, full of hugely interesting rocks – glacial erratics deposited by the retreating ice mass 12,000 years ago. The hard part was going to be getting pieces of a sufficient size up onto the deck without damage or injury. Enter mason Glenn Kresco and his masterful crew, and one very large, very cautiously driven backhoe:

After the old perennials were removed,  Glenn and his guys created several groupings of multi-ton stones to provide sufficient massing on the deck. The largest ones were chained, and ever so gingerly lifted over the railing. The “smaller” stones came by bucket:

Bit by bit a garden begins to appear:

From the above you can see how I am organizing the stones based around outcroppings of large boulders.

The the smaller stones are then positioned around the bigger pieces to form natural looking clusters. Many, if not most, are also buried 1/3 to 2/3 of their mass, to make them appear as if arising from the soil. This is terrifically important, though very rigorous work. Too many small pieces and the rocks look like popcorn scattered on the deck. Too many large boulders and you get a traffic barrier, not a garden. The stones must look right individually for the ensemble to look good as a whole and to enhance our theme of “tumbled farm wall.”

Finally, sufficient soil is brought in to mound around the stones, and the spaces are planted.

Proper plant selection is hugely important. You need species that will appreciate the quick drainage and high temperatures such a garden provides, and most importantly, won’t outgrow their welcome. Dwarf conifers (like the miniature hinoki cypress (left) stonecrop, and  sedums are ideal planted in masses.

So are heathers: their softly colored foliage in shades of chartreuse, gold, gray and green blend beautifully with the stones, and will slowly spread to form mats of color that changes over the seasons. (In fact, by next year, you shouldn’t see much of the mulch at all.)

Their bloom time – August through September – is also well suited for up close appreciation from the pool. One big caveat though: once established, heathers are quite drought resistant, and in fact this planting will require little additional watering after the first year. But until then, this garden needs to be carefully watched to make sure it doesn’t dry to a crisp: it’s hot on that deck, as I can well vouchsafe after having spent a full 90º day planting the material you see above. But I think you’ll agree it was worth it. Properly done, rock gardens are truly a thing of beauty.


Building A Rock Garden — 4 Comments

  1. Awesome garden – I’m actually impressed with our neighbors rock garden in the front of the house. It’s well laid out and has… plants that fit the look although I have no clue what they are. But compared to most amateur yards around here it’s quite nice and low maintenance.

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